1 Scope and purpose
2 Definitions
  2.1 Elements of process control systems
  2.2 Subsystems
  2.3 Analog dc current signal
  2.4 Measured value of an analog dc current signal
  2.5 Range of an analog dc current signal
  2.6 Lower limit
  2.7 Upper limit
  2.8 Load resistance
  2.9 Ripple content
  2.10 Signal common
  2.11 Signal isolation
3 Standard signals
  3.1 Polarity
  3.2 Transmitters
  3.3 Receivers
4 Standard transmitters
  4.1 General
  4.2 System compatibility
  4.3 Classification
  4.4 Load resistance specification
  4.5 Electrical isolation
  4.6 Ripple and noise content
5 Standard receivers
  5.1 Inputs
  5.2 Outputs
  5.3 Isolation
6 System
  6.1 Signal common
  6.2 Power supplies
  6.3 Transmitters
  6.4 Receivers or signal processors
  6.5 Test power sources
7 Appendix